A. Field of the Invention
The present invention relates to an assembly and in particular to an assembly made up of a plurality of parts made of materials having non-compatible ionization characteristics. The assembly may be used in a variety of mechanisms such as fishing reels and bicycle related mechanisms.
B. Description of the Related Art
Fishing reels that are configured to be mounted on a fishing rod for winding a fishing line may be divided into three general categories of reels: spinning reels; double bearing reels; and one-sided bearing reels. Such fishing reels usually include a reel main body to be mounted onto a fishing rod, and a spool mounted on the reel main body for winding a fishing line. In the double bearing reels and the one-sided bearing reels and spool are rotatably supported by the reel main body. Also, in the spinning reels, a spool is configured to move along an axis of the spool in forward and backward directions and is mounted onto the reel main body. Portions of the reel main body, the spool or the like of the fishing reel of each of the above mentioned types of fishing reels are generally made of an aluminum alloy, a synthetic resin, or the like, for the weight reduction purposes.
Portions of the various mechanisms on bicycles are similarly made of materials such as: aluminum alloys; synthetic resins, or the like, for the purpose of reducing the overall weight thereof.
The synthetic-resin-made parts can be manufactured inexpensively and are lightweight and are therefore advantageous for reducing the overall weight of fishing reels and bicycle parts. However, such resin-made parts have a small bending elastic modulus. Therefore, if the rigidity is to be maintained, the thickness of the part must be large and thus the overall weight of the part is increased. Further, it is difficult to obtain surface textures of the part which provide a desirable touch-feeling and difficult to provide a high grade appearance from such resin-made parts.
Aluminum-alloy-made parts are more expensive and larger in weight than the resin-made part, but the bending elastic modulus thereof is larger than that of the resin-made part. Therefore, the small thickness can be attained more easily than the resin-made part, and further an excellent touch-feeling and high grade appearance can be obtained easily. However, the bending elastic modulus is not as large as other metals such as steel, and if sufficient rigidity is to be maintained, the thickness of the part must be undesirably large and the resultant weight is large.
It is conceivable to use a magnesium alloy, which is small in weight and high in rigidity, for these parts. However, it is difficult to use the magnesium alloy for all of the parts because magnesium alloy is expensive, lacks adequate strength, etc. For this reason, other materials are increasingly being sought to use in manufacturing parts. Further, if a part made of magnesium-alloy is used in combination with the parts of other materials, there is a possibility that electrolytic corrosion may occur on the magnesium-alloy-made part due to the contact with the parts of the other materials. The electrolytic corrosion due to contact between two metals, for instance, iron parts with magnesium parts, is a result of incompatible ionization characteristics of the two materials. Specifically, the ionization energy of specific metals are such that some metals corrode when in contact with metals with an ionization energy that is not compatible.